The One Where Rachel Smokes - S5-E18
Continuity mistake: When Ben is playing with the building blocks, they change with each shot, and he holds different coloured blocks each time. (00:15:20)
The One Where Rachel Smokes - S5-E18
Continuity mistake: Joey's snowcone changes during the scene with Ross at the party. It goes from rounded to more flat to rounded, and from plain ice to being able to see the flavoring to ice again. (00:20:00)
Answer: The statements that she's contradicting (that it is common, it happens to every guy, and it's not a big deal), are the things that a woman commonly says to a man who is suffering from erectile difficulty, typically to assuage his bruised ego. However, most men do not believe that these statements are true, as evidenced by Chandler's outburst. He's so caught up in the proof that women are lying about it that he gives himself away.
Rooster of Doom